Improve error message when trying to delete a team that still has a deleted collective #4680
Description
Is your feature request related to a problem? Please describe.
When trying to delete a team that still has a deleted collective connected to it, an non descriptive error message is shown (see nextcloud/collectives#1443) that doesn't give the user any information or direction and just makes managing Teams feel broken.
Describe the solution you'd like
At least give more information in the error message to help the user get around it. (see nextcloud/collectives#1443 again).
Describe alternatives you've considered
On deleting a team, permanently delete its collective as well.
Additional context
No response